1. Technical Background:
The present invention relates generally to medical devices, and more particularly to a balloon catheter for use with an endoscope.
2. Discussion:
There are many different kinds and types of balloon catheters, including for example angioplasty catheters, stent delivery system catheters, etc.
By way of example, the present invention will be described in relation to an esophageal balloon catheter. However, it should be understood that the present invention relates to any balloon catheter having the features recited in any one of the following claims, and is not limited to any particular treatment such as esophageal use, or use with an endoscope, or the particular example embodiments described below.
Balloon catheters often have a relatively flexible tubular shaft having a certain length, which defines one or more tubular passages or “lumens” extending through part or all of the catheter shaft, and has an inflatable balloon attached near one end of the shaft. This end of the catheter where the balloon is located is customarily referred to as the “distal” end, while the other end is called the “proximal” end. The proximal end of the shaft is generally coupled to a hub, which defines an inflation port for connection to an inflator for selectively applying pressure to a fluid inflation medium, thus inflating the balloon. Structurally, the inflation port leads to an inflation lumen defined by the shaft, which extends to and communicates with the interior of the balloon, for the purpose of selectively inflating and deflating the balloon.
When a catheter includes a lumen adapted to slidingly receive a guidewire, it is referred to as a “guidewire lumen,” and it will generally have a proximal and distal “guidewire port.” The distal guidewire port is often at or near the catheter shaft distal end.
A guidewire has a flexible wire-like structure extending from a proximal end to a distal end. The guidewire will usually be of a size selected to fit into and slide within a corresponding guidewire lumen of a catheter.
If a balloon catheter includes a hub affixed to the catheter shaft proximal end, the hub may serve a variety of functions. Such functions may include providing a handle for manipulating the catheter, and/or defining proximal port(s) communicating with lumen(s) defined by the catheter shaft. When there is a guidewire lumen defined by a catheter shaft, its proximal guidewire port may be defined by a proximal hub, referred to as an “over-the-wire” catheter; or the proximal guidewire port may be located at some point along the sidewall of the catheter shaft, referred to as a “rapid exchange” catheter.
When a catheter has no guidewire lumen, but instead has a flexible wire or wire-like distal extension affixed to the catheter, it may be referred to as a “fixed wire” catheter. Whether a particular catheter has a guidewire lumen or has a fixed-wire design, the guidewire or fixed-wire is intended to allow the catheter to more easily select and steer along a desired path.
In a fixed wire balloon catheter, a wire or wire-like structure may simply be attached to the distal end of the balloon catheter. Alternately, a flexible wire or wire-like structure may be affixed to the proximal hub, extending from the proximal end of the catheter, though the shaft and the balloon (perhaps in a dedicated lumen), and may extend a relatively short distance distal of the balloon. In another possible configuration, a distal extension of an inner body of the catheter shaft may serve as a “fixed wire” guiding element.
In general, balloon catheters according to the present invention may have one or more of the following features: (i) a balloon that is longitudinally asymmetrical; and/or (ii) a catheter shaft having a high pull strength.
In greater detail, an asymmetrical balloon may have a cylindrical working portion, flanked by proximal and distal tapering portions, which are in turn flanked by proximal and distal balloon legs, which are affixed to the catheter shaft. A possible feature of a longitudinally asymmetrical balloon is having proximal and distal tapering portions that taper at different angles.
In the case of a balloon catheter for use with an endoscope, the balloon material may be translucent, to allow a physician to use the endoscope to look through the balloon material at the anatomy, so the physician can accurately position the balloon. In addition, the proximal tapering portion of a translucent balloon may have a relatively steep tapering angle, to enhance the clarity of the picture presented to the physician by the endoscope.
Again in the case of a balloon catheter for use with an endoscope, after or during a therapeutic procedure, a physician may wish to retract the balloon catheter back into a passage or lumen defined by the endoscope. Another example may be a balloon catheter for use with a guiding catheter which defines a lumen. During such retraction into an endoscope or guiding catheter, the balloon material of some balloon catheters may possibly “bunch up” toward the distal direction as the balloon catheter is withdrawn back into such a passage or lumen, which may make retraction difficult.
Accordingly, another possible feature of a balloon catheter may be a balloon having a distal tapering portion with a relatively shallow tapering angle, so as to facilitate retraction of the balloon catheter back into an endoscope. The resulting gradual change in distal balloon size may tend to cause the balloon material to more easily fold or pleat and reenter a passage defined by the endoscope, thus reducing retraction force.
Regarding high pull strength, it may be desirable to provide a catheter shaft of a balloon catheter with reinforcement, such as reinforcing braid or strand(s). The resulting stronger catheter shaft will thus exhibit low longitudinal elongation under stress. Accordingly, if retraction becomes difficult, such reinforcing element(s) will tend to resist elongation of the catheter shaft.
An optional additional feature may be one or more visual markers provided on the balloon material or in the balloon material itself. Such visual markers may assist a physician to accurately position the balloon. In the case where a balloon catheter is used with an endoscope, the marker may be viewed visually with the endoscope, by using the endoscopic lens to look through the balloon material of the proximal tapering portion. In other words, the physician's view is provided by an endoscope positioned proximal of the balloon, yet the physician can look through the translucent material of the balloon proximal tapering portion, and see the interior surface of a cylindrical working portion to visualize where the marker(s) is from the “inside.”
Such a visual marker may have any suitable shape or arrangement, including a circumferential band placed at the longitudinal center of the balloon, or a marker placed at one or both of the transitions between a central working portion and the proximal and distal tapering portions. Such markers may enable a physician to use the view through an endoscope to accurately position the balloon at the desired site for treatment, for example centered within a lesion or stricture. Of course, various combinations of these marker arrangements may be used.
In another optional additional feature, the marker(s) may be color-coded. For example, a marker of a particular color may indicate certain properties, such that the catheter balloon is of a particular size, allowing a physician to quickly confirm that the desired size balloon has been selected for use. Visual markers may also be made of different sizes or patterns, to indicate balloon catheter properties.
This disclosure of the present invention will include various possible features and embodiments. However, the present invention scope as set forth in each of the claims, and is not limited to the particular arrangements described in this disclosure.
The terms “tube” and “tubular” are used in their broadest sense, to encompass any structure arranged at a radial distance around a longitudinal axis. Accordingly, the terms “tube” and “tubular” include any structure that (i) is cylindrical or not, such as for example an elliptical or polygonal cross-section, or any other regular or irregular cross-section; (ii) has a different or changing cross-section along its length; (iii) is arranged around a straight, curving, bent or discontinuous longitudinal axis; (iv) has an imperforate surface, or a periodic or other perforate, irregular or gapped surface or cross-section; (v) is spaced uniformly or irregularly, including being spaced varying radial distances from the longitudinal axis; or (vi) has any desired combination of length or cross-sectional size.
Any suitable material may be used to make the components described, including polymers, metals and other materials suitable for use with medical devices.
It is of course possible to build various kinds and designs of catheters according to the present invention, by various techniques and of various materials, to obtain the desired features. It should be noted that the present invention also relates to methods for making and using a balloon catheter, in addition to the balloon catheter itself.
These and various other objects, advantages and features of the invention will become apparent from the following description and claims, when considered in conjunction with the appended drawings. The invention will be explained in greater detail below with reference to the attached drawings of a number of examples of embodiments of the present invention.